Multi-Tenant Cloud Automation Suggestions

Hey guys, i'm looking for a bit of suggestion on multi tenant network design/automation. Mostly looking for your experiences for a single pane of glass for automating and deploying tenants network infrastructure. This is the lay of the land but basically looking at trying to figure out a way to auto spin up firewall instances or at least the configuration piece of this. What have you guys had success with?

Network diagram:

https://imgur.com/a/v52bS9u